hissain

val list = listOf(Student(), Student() ... )
val gson = Gson()
val jsonString = gson.toJson(list)
val sType = object : TypeToken<List<Student>>() { }.type
val otherList = gson.fromJson<List<Student>>(jsonString, sType)

hissain

val list = listOf("String1", "String2" ... )
val gson = Gson()
val jsonString = gson.toJson(list)
val sType = object : TypeToken<List<String>>() { }.type
val otherList = gson.fromJson<List<String>>(jsonString, sType)

hissain

val gSon = GsonBuilder().registerTypeAdapter(Student::class.java, StudentSerializer()).create()
val json = gSon.toJson(student)

hissain

class StudentSerializer : JsonSerializer<Student> {

    override fun serialize(src: Student?, typeOfSrc: Type?, context: JsonSerializationContext?): JsonElement {

        val jsonObject = JsonObject()

        try {

            jsonObject.add("name", context?.serialize(src.name))
            jsonObject.add("address", JsonParser().parse(src.address))

hissain

val gSon = GsonBuilder().registerTypeAdapter(Student::class.java, StudentDeserializer()).create()
val student = gSon.fromJson<Student>(json2, Student::class.java)
/** Output student will be like below **/
student.name // Mark
student.address // { "city": "London", "post": "12000" }

hissain

data class Student(
  var name: String? = null, 
  var address: String? = null) {
}
class StudentDeserializer : JsonDeserializer<Student> {

    override fun deserialize(json: JsonElement, typeOfT: Type, context:     JsonDeserializationContext): Student {
        json as JsonObject

        val name = json.get("name").asString

hissain

val json2 = """
{
   "name": "Mark",
   "address": {
        "city": "London",
        "post": "12000"
    }
 } """

hissain

data class Address(
    var city: String? = null,
    var post: String? = null) {

}

data class Student(
    var name: String? = null,
    var address: Address? = null) {
}

hissain

val json = """
{
   "name": "Alex",
   "address": {
        "city": "Rome",
        "post": "1000"
    }
 } """

hissain

data class Student(  
   @SerializedName("key_name") 
   var name: String? = null, 
   @SerializedName("key_address") 
   var address: String? = null) {
}

val student = Student("Mark", "London, 12000") // object
val json = Gson().toJson(student)  // json string